2 * nvmem framework core.
4 * Copyright (C) 2015 Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
5 * Copyright (C) 2013 Maxime Ripard <maxime.ripard@free-electrons.com>
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License version 2 and
9 * only version 2 as published by the Free Software Foundation.
11 * This program is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 * GNU General Public License for more details.
17 #include <linux/device.h>
18 #include <linux/export.h>
20 #include <linux/idr.h>
21 #include <linux/init.h>
22 #include <linux/module.h>
23 #include <linux/nvmem-consumer.h>
24 #include <linux/nvmem-provider.h>
26 #include <linux/slab.h>
40 struct bin_attribute eeprom;
41 struct device *base_dev;
42 nvmem_reg_read_t reg_read;
43 nvmem_reg_write_t reg_write;
47 #define FLAG_COMPAT BIT(0)
55 struct nvmem_device *nvmem;
56 struct list_head node;
59 static DEFINE_MUTEX(nvmem_mutex);
60 static DEFINE_IDA(nvmem_ida);
62 static LIST_HEAD(nvmem_cells);
63 static DEFINE_MUTEX(nvmem_cells_mutex);
65 #ifdef CONFIG_DEBUG_LOCK_ALLOC
66 static struct lock_class_key eeprom_lock_key;
69 #define to_nvmem_device(d) container_of(d, struct nvmem_device, dev)
70 static int nvmem_reg_read(struct nvmem_device *nvmem, unsigned int offset,
71 void *val, size_t bytes)
74 return nvmem->reg_read(nvmem->priv, offset, val, bytes);
79 static int nvmem_reg_write(struct nvmem_device *nvmem, unsigned int offset,
80 void *val, size_t bytes)
83 return nvmem->reg_write(nvmem->priv, offset, val, bytes);
88 static ssize_t bin_attr_nvmem_read(struct file *filp, struct kobject *kobj,
89 struct bin_attribute *attr,
90 char *buf, loff_t pos, size_t count)
93 struct nvmem_device *nvmem;
99 dev = container_of(kobj, struct device, kobj);
100 nvmem = to_nvmem_device(dev);
102 /* Stop the user from reading */
103 if (pos >= nvmem->size)
106 if (count < nvmem->word_size)
109 if (pos + count > nvmem->size)
110 count = nvmem->size - pos;
112 count = round_down(count, nvmem->word_size);
114 rc = nvmem_reg_read(nvmem, pos, buf, count);
122 static ssize_t bin_attr_nvmem_write(struct file *filp, struct kobject *kobj,
123 struct bin_attribute *attr,
124 char *buf, loff_t pos, size_t count)
127 struct nvmem_device *nvmem;
133 dev = container_of(kobj, struct device, kobj);
134 nvmem = to_nvmem_device(dev);
136 /* Stop the user from writing */
137 if (pos >= nvmem->size)
140 if (count < nvmem->word_size)
143 if (pos + count > nvmem->size)
144 count = nvmem->size - pos;
146 count = round_down(count, nvmem->word_size);
148 rc = nvmem_reg_write(nvmem, pos, buf, count);
156 /* default read/write permissions */
157 static struct bin_attribute bin_attr_rw_nvmem = {
160 .mode = S_IWUSR | S_IRUGO,
162 .read = bin_attr_nvmem_read,
163 .write = bin_attr_nvmem_write,
166 static struct bin_attribute *nvmem_bin_rw_attributes[] = {
171 static const struct attribute_group nvmem_bin_rw_group = {
172 .bin_attrs = nvmem_bin_rw_attributes,
175 static const struct attribute_group *nvmem_rw_dev_groups[] = {
180 /* read only permission */
181 static struct bin_attribute bin_attr_ro_nvmem = {
186 .read = bin_attr_nvmem_read,
189 static struct bin_attribute *nvmem_bin_ro_attributes[] = {
194 static const struct attribute_group nvmem_bin_ro_group = {
195 .bin_attrs = nvmem_bin_ro_attributes,
198 static const struct attribute_group *nvmem_ro_dev_groups[] = {
203 /* default read/write permissions, root only */
204 static struct bin_attribute bin_attr_rw_root_nvmem = {
207 .mode = S_IWUSR | S_IRUSR,
209 .read = bin_attr_nvmem_read,
210 .write = bin_attr_nvmem_write,
213 static struct bin_attribute *nvmem_bin_rw_root_attributes[] = {
214 &bin_attr_rw_root_nvmem,
218 static const struct attribute_group nvmem_bin_rw_root_group = {
219 .bin_attrs = nvmem_bin_rw_root_attributes,
222 static const struct attribute_group *nvmem_rw_root_dev_groups[] = {
223 &nvmem_bin_rw_root_group,
227 /* read only permission, root only */
228 static struct bin_attribute bin_attr_ro_root_nvmem = {
233 .read = bin_attr_nvmem_read,
236 static struct bin_attribute *nvmem_bin_ro_root_attributes[] = {
237 &bin_attr_ro_root_nvmem,
241 static const struct attribute_group nvmem_bin_ro_root_group = {
242 .bin_attrs = nvmem_bin_ro_root_attributes,
245 static const struct attribute_group *nvmem_ro_root_dev_groups[] = {
246 &nvmem_bin_ro_root_group,
250 static void nvmem_release(struct device *dev)
252 struct nvmem_device *nvmem = to_nvmem_device(dev);
254 ida_simple_remove(&nvmem_ida, nvmem->id);
258 static const struct device_type nvmem_provider_type = {
259 .release = nvmem_release,
262 static struct bus_type nvmem_bus_type = {
266 static int of_nvmem_match(struct device *dev, void *nvmem_np)
268 return dev->of_node == nvmem_np;
271 static struct nvmem_device *of_nvmem_find(struct device_node *nvmem_np)
278 d = bus_find_device(&nvmem_bus_type, NULL, nvmem_np, of_nvmem_match);
283 return to_nvmem_device(d);
286 static struct nvmem_cell *nvmem_find_cell(const char *cell_id)
288 struct nvmem_cell *p;
290 list_for_each_entry(p, &nvmem_cells, node)
291 if (p && !strcmp(p->name, cell_id))
297 static void nvmem_cell_drop(struct nvmem_cell *cell)
299 mutex_lock(&nvmem_cells_mutex);
300 list_del(&cell->node);
301 mutex_unlock(&nvmem_cells_mutex);
305 static void nvmem_device_remove_all_cells(const struct nvmem_device *nvmem)
307 struct nvmem_cell *cell;
308 struct list_head *p, *n;
310 list_for_each_safe(p, n, &nvmem_cells) {
311 cell = list_entry(p, struct nvmem_cell, node);
312 if (cell->nvmem == nvmem)
313 nvmem_cell_drop(cell);
317 static void nvmem_cell_add(struct nvmem_cell *cell)
319 mutex_lock(&nvmem_cells_mutex);
320 list_add_tail(&cell->node, &nvmem_cells);
321 mutex_unlock(&nvmem_cells_mutex);
324 static int nvmem_cell_info_to_nvmem_cell(struct nvmem_device *nvmem,
325 const struct nvmem_cell_info *info,
326 struct nvmem_cell *cell)
329 cell->offset = info->offset;
330 cell->bytes = info->bytes;
331 cell->name = info->name;
333 cell->bit_offset = info->bit_offset;
334 cell->nbits = info->nbits;
337 cell->bytes = DIV_ROUND_UP(cell->nbits + cell->bit_offset,
340 if (!IS_ALIGNED(cell->offset, nvmem->stride)) {
342 "cell %s unaligned to nvmem stride %d\n",
343 cell->name, nvmem->stride);
350 static int nvmem_add_cells(struct nvmem_device *nvmem,
351 const struct nvmem_config *cfg)
353 struct nvmem_cell **cells;
354 const struct nvmem_cell_info *info = cfg->cells;
357 cells = kcalloc(cfg->ncells, sizeof(*cells), GFP_KERNEL);
361 for (i = 0; i < cfg->ncells; i++) {
362 cells[i] = kzalloc(sizeof(**cells), GFP_KERNEL);
368 rval = nvmem_cell_info_to_nvmem_cell(nvmem, &info[i], cells[i]);
374 nvmem_cell_add(cells[i]);
377 nvmem->ncells = cfg->ncells;
378 /* remove tmp array */
384 nvmem_cell_drop(cells[i]);
392 * nvmem_setup_compat() - Create an additional binary entry in
393 * drivers sys directory, to be backwards compatible with the older
394 * drivers/misc/eeprom drivers.
396 static int nvmem_setup_compat(struct nvmem_device *nvmem,
397 const struct nvmem_config *config)
401 if (!config->base_dev)
404 if (nvmem->read_only)
405 nvmem->eeprom = bin_attr_ro_root_nvmem;
407 nvmem->eeprom = bin_attr_rw_root_nvmem;
408 nvmem->eeprom.attr.name = "eeprom";
409 nvmem->eeprom.size = nvmem->size;
410 #ifdef CONFIG_DEBUG_LOCK_ALLOC
411 nvmem->eeprom.attr.key = &eeprom_lock_key;
413 nvmem->eeprom.private = &nvmem->dev;
414 nvmem->base_dev = config->base_dev;
416 rval = device_create_bin_file(nvmem->base_dev, &nvmem->eeprom);
419 "Failed to create eeprom binary file %d\n", rval);
423 nvmem->flags |= FLAG_COMPAT;
429 * nvmem_register() - Register a nvmem device for given nvmem_config.
430 * Also creates an binary entry in /sys/bus/nvmem/devices/dev-name/nvmem
432 * @config: nvmem device configuration with which nvmem device is created.
434 * Return: Will be an ERR_PTR() on error or a valid pointer to nvmem_device
438 struct nvmem_device *nvmem_register(const struct nvmem_config *config)
440 struct nvmem_device *nvmem;
441 struct device_node *np;
445 return ERR_PTR(-EINVAL);
447 nvmem = kzalloc(sizeof(*nvmem), GFP_KERNEL);
449 return ERR_PTR(-ENOMEM);
451 rval = ida_simple_get(&nvmem_ida, 0, 0, GFP_KERNEL);
454 return ERR_PTR(rval);
458 nvmem->owner = config->owner;
459 nvmem->stride = config->stride;
460 nvmem->word_size = config->word_size;
461 nvmem->size = config->size;
462 nvmem->dev.type = &nvmem_provider_type;
463 nvmem->dev.bus = &nvmem_bus_type;
464 nvmem->dev.parent = config->dev;
465 nvmem->priv = config->priv;
466 nvmem->reg_read = config->reg_read;
467 nvmem->reg_write = config->reg_write;
468 np = config->dev->of_node;
469 nvmem->dev.of_node = np;
470 dev_set_name(&nvmem->dev, "%s%d",
471 config->name ? : "nvmem", config->id);
473 nvmem->read_only = of_property_read_bool(np, "read-only") |
476 if (config->root_only)
477 nvmem->dev.groups = nvmem->read_only ?
478 nvmem_ro_root_dev_groups :
479 nvmem_rw_root_dev_groups;
481 nvmem->dev.groups = nvmem->read_only ?
482 nvmem_ro_dev_groups :
485 device_initialize(&nvmem->dev);
487 dev_dbg(&nvmem->dev, "Registering nvmem device %s\n", config->name);
489 rval = device_add(&nvmem->dev);
493 if (config->compat) {
494 rval = nvmem_setup_compat(nvmem, config);
500 nvmem_add_cells(nvmem, config);
504 ida_simple_remove(&nvmem_ida, nvmem->id);
506 return ERR_PTR(rval);
508 EXPORT_SYMBOL_GPL(nvmem_register);
511 * nvmem_unregister() - Unregister previously registered nvmem device
513 * @nvmem: Pointer to previously registered nvmem device.
515 * Return: Will be an negative on error or a zero on success.
517 int nvmem_unregister(struct nvmem_device *nvmem)
519 mutex_lock(&nvmem_mutex);
521 mutex_unlock(&nvmem_mutex);
524 mutex_unlock(&nvmem_mutex);
526 if (nvmem->flags & FLAG_COMPAT)
527 device_remove_bin_file(nvmem->base_dev, &nvmem->eeprom);
529 nvmem_device_remove_all_cells(nvmem);
530 device_del(&nvmem->dev);
534 EXPORT_SYMBOL_GPL(nvmem_unregister);
536 static struct nvmem_device *__nvmem_device_get(struct device_node *np,
537 struct nvmem_cell **cellp,
540 struct nvmem_device *nvmem = NULL;
542 mutex_lock(&nvmem_mutex);
545 nvmem = of_nvmem_find(np);
547 mutex_unlock(&nvmem_mutex);
548 return ERR_PTR(-EPROBE_DEFER);
551 struct nvmem_cell *cell = nvmem_find_cell(cell_id);
559 mutex_unlock(&nvmem_mutex);
560 return ERR_PTR(-ENOENT);
565 mutex_unlock(&nvmem_mutex);
567 if (!try_module_get(nvmem->owner)) {
569 "could not increase module refcount for cell %s\n",
572 mutex_lock(&nvmem_mutex);
574 mutex_unlock(&nvmem_mutex);
576 return ERR_PTR(-EINVAL);
582 static void __nvmem_device_put(struct nvmem_device *nvmem)
584 module_put(nvmem->owner);
585 mutex_lock(&nvmem_mutex);
587 mutex_unlock(&nvmem_mutex);
590 static int nvmem_match(struct device *dev, void *data)
592 return !strcmp(dev_name(dev), data);
595 static struct nvmem_device *nvmem_find(const char *name)
599 d = bus_find_device(&nvmem_bus_type, NULL, (void *)name, nvmem_match);
604 return to_nvmem_device(d);
607 #if IS_ENABLED(CONFIG_NVMEM) && IS_ENABLED(CONFIG_OF)
609 * of_nvmem_device_get() - Get nvmem device from a given id
611 * @np: Device tree node that uses the nvmem device.
612 * @id: nvmem name from nvmem-names property.
614 * Return: ERR_PTR() on error or a valid pointer to a struct nvmem_device
617 struct nvmem_device *of_nvmem_device_get(struct device_node *np, const char *id)
620 struct device_node *nvmem_np;
623 index = of_property_match_string(np, "nvmem-names", id);
625 nvmem_np = of_parse_phandle(np, "nvmem", index);
627 return ERR_PTR(-EINVAL);
629 return __nvmem_device_get(nvmem_np, NULL, NULL);
631 EXPORT_SYMBOL_GPL(of_nvmem_device_get);
635 * nvmem_device_get() - Get nvmem device from a given id
637 * @dev: Device that uses the nvmem device.
638 * @dev_name: name of the requested nvmem device.
640 * Return: ERR_PTR() on error or a valid pointer to a struct nvmem_device
643 struct nvmem_device *nvmem_device_get(struct device *dev, const char *dev_name)
645 if (dev->of_node) { /* try dt first */
646 struct nvmem_device *nvmem;
648 nvmem = of_nvmem_device_get(dev->of_node, dev_name);
650 if (!IS_ERR(nvmem) || PTR_ERR(nvmem) == -EPROBE_DEFER)
655 return nvmem_find(dev_name);
657 EXPORT_SYMBOL_GPL(nvmem_device_get);
659 static int devm_nvmem_device_match(struct device *dev, void *res, void *data)
661 struct nvmem_device **nvmem = res;
663 if (WARN_ON(!nvmem || !*nvmem))
666 return *nvmem == data;
669 static void devm_nvmem_device_release(struct device *dev, void *res)
671 nvmem_device_put(*(struct nvmem_device **)res);
675 * devm_nvmem_device_put() - put alredy got nvmem device
677 * @dev: Device that uses the nvmem device.
678 * @nvmem: pointer to nvmem device allocated by devm_nvmem_cell_get(),
679 * that needs to be released.
681 void devm_nvmem_device_put(struct device *dev, struct nvmem_device *nvmem)
685 ret = devres_release(dev, devm_nvmem_device_release,
686 devm_nvmem_device_match, nvmem);
690 EXPORT_SYMBOL_GPL(devm_nvmem_device_put);
693 * nvmem_device_put() - put alredy got nvmem device
695 * @nvmem: pointer to nvmem device that needs to be released.
697 void nvmem_device_put(struct nvmem_device *nvmem)
699 __nvmem_device_put(nvmem);
701 EXPORT_SYMBOL_GPL(nvmem_device_put);
704 * devm_nvmem_device_get() - Get nvmem cell of device form a given id
706 * @dev: Device that requests the nvmem device.
707 * @id: name id for the requested nvmem device.
709 * Return: ERR_PTR() on error or a valid pointer to a struct nvmem_cell
710 * on success. The nvmem_cell will be freed by the automatically once the
713 struct nvmem_device *devm_nvmem_device_get(struct device *dev, const char *id)
715 struct nvmem_device **ptr, *nvmem;
717 ptr = devres_alloc(devm_nvmem_device_release, sizeof(*ptr), GFP_KERNEL);
719 return ERR_PTR(-ENOMEM);
721 nvmem = nvmem_device_get(dev, id);
722 if (!IS_ERR(nvmem)) {
724 devres_add(dev, ptr);
731 EXPORT_SYMBOL_GPL(devm_nvmem_device_get);
733 static struct nvmem_cell *nvmem_cell_get_from_list(const char *cell_id)
735 struct nvmem_cell *cell = NULL;
736 struct nvmem_device *nvmem;
738 nvmem = __nvmem_device_get(NULL, &cell, cell_id);
740 return ERR_CAST(nvmem);
745 #if IS_ENABLED(CONFIG_NVMEM) && IS_ENABLED(CONFIG_OF)
747 * of_nvmem_cell_get() - Get a nvmem cell from given device node and cell id
749 * @np: Device tree node that uses the nvmem cell.
750 * @name: nvmem cell name from nvmem-cell-names property, or NULL
751 * for the cell at index 0 (the lone cell with no accompanying
752 * nvmem-cell-names property).
754 * Return: Will be an ERR_PTR() on error or a valid pointer
755 * to a struct nvmem_cell. The nvmem_cell will be freed by the
758 struct nvmem_cell *of_nvmem_cell_get(struct device_node *np,
761 struct device_node *cell_np, *nvmem_np;
762 struct nvmem_cell *cell;
763 struct nvmem_device *nvmem;
768 /* if cell name exists, find index to the name */
770 index = of_property_match_string(np, "nvmem-cell-names", name);
772 cell_np = of_parse_phandle(np, "nvmem-cells", index);
774 return ERR_PTR(-EINVAL);
776 nvmem_np = of_get_next_parent(cell_np);
778 return ERR_PTR(-EINVAL);
780 nvmem = __nvmem_device_get(nvmem_np, NULL, NULL);
782 return ERR_CAST(nvmem);
784 addr = of_get_property(cell_np, "reg", &len);
785 if (!addr || (len < 2 * sizeof(u32))) {
786 dev_err(&nvmem->dev, "nvmem: invalid reg on %s\n",
792 cell = kzalloc(sizeof(*cell), GFP_KERNEL);
799 cell->offset = be32_to_cpup(addr++);
800 cell->bytes = be32_to_cpup(addr);
801 cell->name = cell_np->name;
803 addr = of_get_property(cell_np, "bits", &len);
804 if (addr && len == (2 * sizeof(u32))) {
805 cell->bit_offset = be32_to_cpup(addr++);
806 cell->nbits = be32_to_cpup(addr);
810 cell->bytes = DIV_ROUND_UP(cell->nbits + cell->bit_offset,
813 if (!IS_ALIGNED(cell->offset, nvmem->stride)) {
815 "cell %s unaligned to nvmem stride %d\n",
816 cell->name, nvmem->stride);
821 nvmem_cell_add(cell);
829 __nvmem_device_put(nvmem);
831 return ERR_PTR(rval);
833 EXPORT_SYMBOL_GPL(of_nvmem_cell_get);
837 * nvmem_cell_get() - Get nvmem cell of device form a given cell name
839 * @dev: Device that requests the nvmem cell.
840 * @cell_id: nvmem cell name to get.
842 * Return: Will be an ERR_PTR() on error or a valid pointer
843 * to a struct nvmem_cell. The nvmem_cell will be freed by the
846 struct nvmem_cell *nvmem_cell_get(struct device *dev, const char *cell_id)
848 struct nvmem_cell *cell;
850 if (dev->of_node) { /* try dt first */
851 cell = of_nvmem_cell_get(dev->of_node, cell_id);
852 if (!IS_ERR(cell) || PTR_ERR(cell) == -EPROBE_DEFER)
856 return nvmem_cell_get_from_list(cell_id);
858 EXPORT_SYMBOL_GPL(nvmem_cell_get);
860 static void devm_nvmem_cell_release(struct device *dev, void *res)
862 nvmem_cell_put(*(struct nvmem_cell **)res);
866 * devm_nvmem_cell_get() - Get nvmem cell of device form a given id
868 * @dev: Device that requests the nvmem cell.
869 * @id: nvmem cell name id to get.
871 * Return: Will be an ERR_PTR() on error or a valid pointer
872 * to a struct nvmem_cell. The nvmem_cell will be freed by the
873 * automatically once the device is freed.
875 struct nvmem_cell *devm_nvmem_cell_get(struct device *dev, const char *id)
877 struct nvmem_cell **ptr, *cell;
879 ptr = devres_alloc(devm_nvmem_cell_release, sizeof(*ptr), GFP_KERNEL);
881 return ERR_PTR(-ENOMEM);
883 cell = nvmem_cell_get(dev, id);
886 devres_add(dev, ptr);
893 EXPORT_SYMBOL_GPL(devm_nvmem_cell_get);
895 static int devm_nvmem_cell_match(struct device *dev, void *res, void *data)
897 struct nvmem_cell **c = res;
899 if (WARN_ON(!c || !*c))
906 * devm_nvmem_cell_put() - Release previously allocated nvmem cell
907 * from devm_nvmem_cell_get.
909 * @dev: Device that requests the nvmem cell.
910 * @cell: Previously allocated nvmem cell by devm_nvmem_cell_get().
912 void devm_nvmem_cell_put(struct device *dev, struct nvmem_cell *cell)
916 ret = devres_release(dev, devm_nvmem_cell_release,
917 devm_nvmem_cell_match, cell);
921 EXPORT_SYMBOL(devm_nvmem_cell_put);
924 * nvmem_cell_put() - Release previously allocated nvmem cell.
926 * @cell: Previously allocated nvmem cell by nvmem_cell_get().
928 void nvmem_cell_put(struct nvmem_cell *cell)
930 struct nvmem_device *nvmem = cell->nvmem;
932 __nvmem_device_put(nvmem);
933 nvmem_cell_drop(cell);
935 EXPORT_SYMBOL_GPL(nvmem_cell_put);
937 static inline void nvmem_shift_read_buffer_in_place(struct nvmem_cell *cell,
941 int i, bit_offset = cell->bit_offset;
948 /* setup rest of the bytes if any */
949 for (i = 1; i < cell->bytes; i++) {
950 /* Get bits from next byte and shift them towards msb */
951 *p |= *b << (BITS_PER_BYTE - bit_offset);
957 /* result fits in less bytes */
958 if (cell->bytes != DIV_ROUND_UP(cell->nbits, BITS_PER_BYTE))
961 /* clear msb bits if any leftover in the last byte */
962 *p &= GENMASK((cell->nbits%BITS_PER_BYTE) - 1, 0);
965 static int __nvmem_cell_read(struct nvmem_device *nvmem,
966 struct nvmem_cell *cell,
967 void *buf, size_t *len)
971 rc = nvmem_reg_read(nvmem, cell->offset, buf, cell->bytes);
976 /* shift bits in-place */
977 if (cell->bit_offset || cell->nbits)
978 nvmem_shift_read_buffer_in_place(cell, buf);
987 * nvmem_cell_read() - Read a given nvmem cell
989 * @cell: nvmem cell to be read.
990 * @len: pointer to length of cell which will be populated on successful read;
993 * Return: ERR_PTR() on error or a valid pointer to a buffer on success. The
994 * buffer should be freed by the consumer with a kfree().
996 void *nvmem_cell_read(struct nvmem_cell *cell, size_t *len)
998 struct nvmem_device *nvmem = cell->nvmem;
1003 return ERR_PTR(-EINVAL);
1005 buf = kzalloc(cell->bytes, GFP_KERNEL);
1007 return ERR_PTR(-ENOMEM);
1009 rc = __nvmem_cell_read(nvmem, cell, buf, len);
1017 EXPORT_SYMBOL_GPL(nvmem_cell_read);
1019 static inline void *nvmem_cell_prepare_write_buffer(struct nvmem_cell *cell,
1022 struct nvmem_device *nvmem = cell->nvmem;
1023 int i, rc, nbits, bit_offset = cell->bit_offset;
1024 u8 v, *p, *buf, *b, pbyte, pbits;
1026 nbits = cell->nbits;
1027 buf = kzalloc(cell->bytes, GFP_KERNEL);
1029 return ERR_PTR(-ENOMEM);
1031 memcpy(buf, _buf, len);
1038 /* setup the first byte with lsb bits from nvmem */
1039 rc = nvmem_reg_read(nvmem, cell->offset, &v, 1);
1040 *b++ |= GENMASK(bit_offset - 1, 0) & v;
1042 /* setup rest of the byte if any */
1043 for (i = 1; i < cell->bytes; i++) {
1044 /* Get last byte bits and shift them towards lsb */
1045 pbits = pbyte >> (BITS_PER_BYTE - 1 - bit_offset);
1053 /* if it's not end on byte boundary */
1054 if ((nbits + bit_offset) % BITS_PER_BYTE) {
1055 /* setup the last byte with msb bits from nvmem */
1056 rc = nvmem_reg_read(nvmem,
1057 cell->offset + cell->bytes - 1, &v, 1);
1058 *p |= GENMASK(7, (nbits + bit_offset) % BITS_PER_BYTE) & v;
1066 * nvmem_cell_write() - Write to a given nvmem cell
1068 * @cell: nvmem cell to be written.
1069 * @buf: Buffer to be written.
1070 * @len: length of buffer to be written to nvmem cell.
1072 * Return: length of bytes written or negative on failure.
1074 int nvmem_cell_write(struct nvmem_cell *cell, void *buf, size_t len)
1076 struct nvmem_device *nvmem = cell->nvmem;
1079 if (!nvmem || nvmem->read_only ||
1080 (cell->bit_offset == 0 && len != cell->bytes))
1083 if (cell->bit_offset || cell->nbits) {
1084 buf = nvmem_cell_prepare_write_buffer(cell, buf, len);
1086 return PTR_ERR(buf);
1089 rc = nvmem_reg_write(nvmem, cell->offset, buf, cell->bytes);
1091 /* free the tmp buffer */
1092 if (cell->bit_offset || cell->nbits)
1100 EXPORT_SYMBOL_GPL(nvmem_cell_write);
1103 * nvmem_device_cell_read() - Read a given nvmem device and cell
1105 * @nvmem: nvmem device to read from.
1106 * @info: nvmem cell info to be read.
1107 * @buf: buffer pointer which will be populated on successful read.
1109 * Return: length of successful bytes read on success and negative
1110 * error code on error.
1112 ssize_t nvmem_device_cell_read(struct nvmem_device *nvmem,
1113 struct nvmem_cell_info *info, void *buf)
1115 struct nvmem_cell cell;
1122 rc = nvmem_cell_info_to_nvmem_cell(nvmem, info, &cell);
1126 rc = __nvmem_cell_read(nvmem, &cell, buf, &len);
1132 EXPORT_SYMBOL_GPL(nvmem_device_cell_read);
1135 * nvmem_device_cell_write() - Write cell to a given nvmem device
1137 * @nvmem: nvmem device to be written to.
1138 * @info: nvmem cell info to be written.
1139 * @buf: buffer to be written to cell.
1141 * Return: length of bytes written or negative error code on failure.
1143 int nvmem_device_cell_write(struct nvmem_device *nvmem,
1144 struct nvmem_cell_info *info, void *buf)
1146 struct nvmem_cell cell;
1152 rc = nvmem_cell_info_to_nvmem_cell(nvmem, info, &cell);
1156 return nvmem_cell_write(&cell, buf, cell.bytes);
1158 EXPORT_SYMBOL_GPL(nvmem_device_cell_write);
1161 * nvmem_device_read() - Read from a given nvmem device
1163 * @nvmem: nvmem device to read from.
1164 * @offset: offset in nvmem device.
1165 * @bytes: number of bytes to read.
1166 * @buf: buffer pointer which will be populated on successful read.
1168 * Return: length of successful bytes read on success and negative
1169 * error code on error.
1171 int nvmem_device_read(struct nvmem_device *nvmem,
1172 unsigned int offset,
1173 size_t bytes, void *buf)
1180 rc = nvmem_reg_read(nvmem, offset, buf, bytes);
1187 EXPORT_SYMBOL_GPL(nvmem_device_read);
1190 * nvmem_device_write() - Write cell to a given nvmem device
1192 * @nvmem: nvmem device to be written to.
1193 * @offset: offset in nvmem device.
1194 * @bytes: number of bytes to write.
1195 * @buf: buffer to be written.
1197 * Return: length of bytes written or negative error code on failure.
1199 int nvmem_device_write(struct nvmem_device *nvmem,
1200 unsigned int offset,
1201 size_t bytes, void *buf)
1208 rc = nvmem_reg_write(nvmem, offset, buf, bytes);
1216 EXPORT_SYMBOL_GPL(nvmem_device_write);
1218 static int __init nvmem_init(void)
1220 return bus_register(&nvmem_bus_type);
1223 static void __exit nvmem_exit(void)
1225 bus_unregister(&nvmem_bus_type);
1228 subsys_initcall(nvmem_init);
1229 module_exit(nvmem_exit);
1231 MODULE_AUTHOR("Srinivas Kandagatla <srinivas.kandagatla@linaro.org");
1232 MODULE_AUTHOR("Maxime Ripard <maxime.ripard@free-electrons.com");
1233 MODULE_DESCRIPTION("nvmem Driver Core");
1234 MODULE_LICENSE("GPL v2");